JP2002182037A - Method for manufacturing mold release film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a mold release film capable of facilitating the detection of foreign matters and defects in a polarizer, an optical retardation polarizing plate and an optical retardation plate for a large- sized TFT(thin film transistor) system or a STN(super twisted nematic) system by a visual inspection. SOLUTION: In the method for manufacturing the mold release film, on which a release layer mainly consisting of a silicone resin is formed by applying a coating liquid containing polydimethylsiloxane having a vinyl group and a hydrogen silane based compound in a specified ratio onto the surface of a polyester film and subsequently thermosetting the liquid, the polyester film satisfies that retardation value (R) is >=1,200 (nm), MOR(maximum oriented ratio) value measured by a microwave transmission molecular orientation meter is 1.3-1.8, difference between the minimum and maximum values of the MOR values is <=0.2 and number of pieces of foreign matters per 310.8 cm2 area is zero in the range of >=25 μm and is <=10 in the range of >=5 μm and <25 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a release film, and more particularly, to a method of laminating a release film obtained by the present invention when inspecting a polarizing plate, a phase difference polarizing plate or a phase difference plate for foreign substances. The present invention relates to a method for manufacturing a release film that can easily perform a foreign substance inspection when used.

[0002]

2. Description of the Related Art In recent years, liquid crystal displays (LCDs) have been improved in performance, image quality, color, and screen size, and CRT (Cathode Ray Tube) has been developed.
Since they can be made lighter and consume less energy than displays, they are widely used in displays such as notebook personal computers or word processors, and are rapidly spreading and growing remarkably.

[0003] However, further growth of LCDs requires price reductions, and cost rationalization is an important point. A large-screen TFT (Thin Film Transistor) having a particularly high defective product occurrence rate
There is an urgent need to rationalize costs by improving the yield of LCDs of the active matrix type or STN (super twisted nematic) type.

In an LCD, a polarizing plate, a phase difference polarizing plate, or a phase difference plate is used to make light and dark of transmitted light of the LCD,
It is necessary and important part to change hue,
Also for these, maintaining stable quality is an important issue, and at present the standards for process inspection, quality inspection, and shipping inspection are becoming increasingly strict.

A polarizing plate, a retardation polarizing plate or a retardation plate is provided by providing an adhesive layer on one surface of a polarizing base material, and further transporting a laminate obtained by further laminating a release film on the adhesive layer in a roll state. Or kept. Then, when manufacturing the LCD, each laminate is taken out from a roll, punched into various sizes, cut, and provided for manufacturing the LCD.

Further, a part of the sheet is punched into various sizes from a roll-shaped laminate, cut, and then transported or stored in a sheet form. However, the conventional release film has a disadvantage that the silicone resin in the release layer and the components in the pressure-sensitive adhesive act during storage for a long period of time as a laminate, making separation and separation difficult. Further, unreacted substances and the like existing in the release layer during storage for a long period of time are transferred to the surface of the pressure-sensitive adhesive, which causes a serious drawback that the pressure-sensitive adhesive strength is reduced.

[0007] One of the important items in the inspection of these laminates used in the manufacture of LCDs is the inspection of foreign matter contamination and adhesion. This includes not only the polarizing plate polarizer manufacturing process but also separation. It is important to control foreign substances in all processes from the adhesive lamination process to the die film, the punching and cutting process, and the curing and shipping process.

However, the foreign substance inspection of the above-mentioned laminate is performed by the cross Nicol method (a method in which two polarizing plates are arranged with their stretching axes perpendicular to each other, a sample film is inserted between the polarizing plates, and foreign substances are inspected by transmitted light). It is a visual inspection of, especially for large screen, accurate visual inspection may be hindered due to the optical anisotropy of the biaxially oriented polyester film that is the base of the release film, Oversight of foreign matter has occurred at a considerable frequency.

As the base film of the release film, a biaxially oriented polyester film is usually used. In particular, mechanical properties and thermal properties are balanced in the vertical direction (longitudinal direction) and the horizontal direction (width direction). An axially oriented polyethylene terephthalate film is used. The direction of the main axis of the crystal orientation of the biaxially oriented polyester film does not coincide with either the longitudinal direction or the lateral direction of the film, and is substantially at the middle of both directions. Further, the direction of the main axis of the crystal orientation greatly changes depending on the position in the transverse direction (width direction) of the film. This change is due to the bowing phenomenon at the time of film formation, and becomes larger as it approaches the both ends than the center.

On the other hand, a polarizing plate, a retardation polarizing plate, or a retardation plate is produced using a uniaxially polarizing film, and the direction of the orientation axis is usually a vertical direction.

Therefore, when a long polarizing plate, a phase difference polarizing plate or a phase difference plate and a release film taken out of a roll are laminated, the direction of the orientation axis of the polarizing plate, the phase difference polarizing plate or the phase difference plate is changed. The direction of the main axis of crystal orientation of the biaxially oriented polyester film constituting the release film is shifted, and the direction of the main axis of crystal orientation of the biaxially oriented polyester film gradually changes from the center to the end of the film.
In particular, the deviation increases as the distance to both ends increases. For this reason, when a visual foreign substance inspection of the obtained laminated film (a polarizing plate, a phase difference polarizing plate or a laminate of a phase difference plate and a release film) is performed by the crossed Nicols method, light interference colors are generated, and both ends of the film are caused. The closer the distance is to the above, the stronger this degree becomes, and the more difficult it is to inspect foreign matter.

When the width of the laminate is narrow, in other words, L
When the CD is small, the accuracy of visual foreign matter inspection can be secured to some extent even if the light interference color is slightly present, but if the width is wide,
In other words, when the LCD has a large screen, it is extremely difficult to check all foreign substances by visual foreign substance inspection.

If there is a foreign substance which can be optically detected in the biaxially oriented polyester film constituting the release film, a polarizing plate, a phase difference polarizing plate or a phase difference plate is required for visual inspection of the laminate. Therefore, it is difficult to accurately detect a foreign substance because the foreign substance cannot be distinguished from a foreign substance existing in the apparatus.

[0014]

SUMMARY OF THE INVENTION An object of the present invention is to overcome the disadvantages of the prior art, to enable the adhesive to be peeled off with an appropriate force (has good releasability), and to improve the stability over time. Excellent, furthermore, when laminated with a polarizing plate, a retardation polarizing plate or a retardation plate, the light interference color does not substantially occur, facilitating visual inspection of foreign substances by the crossed Nicols method, and particularly a large-screen LCD.
In use, the detection accuracy is improved by minimizing the oversight of foreign matter as much as possible to prevent the occurrence of defective products, and the quality of detection is improved by increasing the detection accuracy of foreign matter present in the polarizing plate, retardation polarizing plate or retardation plate. It is an object of the present invention to provide a method for manufacturing a release film used for improving the yield rate of the film.

[0015]

According to the present invention, an object of the present invention is to apply a coating liquid containing an addition-polymerizable silicone resin to at least one surface of a polyester film, and then to heat and cure the silicone resin to thereby mainly cure the silicone resin. A method for producing a release film having a release layer as a component, wherein the polyester film has a retardation value (R) defined by the following formula (1) of not less than 1200 (nm) and a microwave transmission property. MOR value measured by a type molecular orientation meter is 1.3.
~ 1.8, the difference between the minimum value and the maximum value of the MOR value is 0.2 or less, and the width (area 310.mm) of 210 mm in one side and 148 mm in the side perpendicular to it.
8 cm ² ) of a film containing no foreign matter having a size of 25 μm or more, having 10 or less foreign matters having a size of 5 μm to less than 25 μm, and having a vinyl group-containing polydimethylsiloxane before curing of the silicone resin; The ratio of the base compound is such that the amount of the SiH group in the hydrogensilane-based compound is 1.0 to 2.0 mol per 1.0 mol of the vinyl group in the polydimethylsiloxane having a vinyl group, and wavenumber by -CH ₃ observed in the infrared absorption spectrum of the silicone resin after 2800-300
Absorption peak height of 0 cm ^-1 and (Ha), the absorption peak height of the wave number 2100～2300Cm ^-1 by -SiH (H
This is achieved by a method for producing a polarizing plate, a retardation polarizing plate or a release film used for inspection of a retardation plate, wherein the ratio of b) satisfies the following expression (2).

[0016]

R = △ n · d Equation (1) (where, in Equation (1), Δn is the visible light (wavelength λ) of the film.
= 589 nm), the difference (nx-ny) between the refractive index (nx) in the film width direction and the refractive index (ny) in the direction perpendicular to the film width, and d is the thickness (nm) of the film. )

[0017]

## EQU4 ## 0 ≦ Hb / Ha ≦ 0.05 Equation (2)

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

[Polyester Film] In the present invention, a biaxially oriented polyester film is used as a base film of the release film. The polyester constituting the base film is a linear polyester comprising a dicarboxylic acid component and a glycol component. .

Examples of the dicarboxylic acid component include aromatic dicarboxylic acids such as terephthalic acid, 2,6-naphthalenedicarboxylic acid, isophthalic acid, and 4,4'-diphenyldicarboxylic acid. 2,6-Naphthalenedicarboxylic acid is preferred.

Examples of the glycol component include ethylene glycol, diethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, and 1,6-hexanediol. , 1,4-cyclohexane dimethanol and the like.
Ethylene glycol is preferred.

The polyester constituting the base film in the present invention is polyethylene terephthalate or polyethylene-2,6-
Naphthalate is preferred because the base film has excellent mechanical properties and thermal properties.

The above-mentioned polyester may be a polyester obtained by copolymerizing the above-mentioned dicarboxylic acid component or glycol component or the like. (E.g., 5 mol% or less) and may be a small amount of copolymerized polyester.

The biaxially oriented polyester film used for the base film in the present invention has a retardation value (R) defined by the above formula (1) of not less than 1200 (nm) and is measured by a microwave transmission type molecular orientation meter. MOR
Value is in the range of 1.3 to 1.8, the difference between the minimum value and the maximum value of the MOR value is 0.2 or less, and the length of one side is 21
In a film per area (310.8 cm ² ) having a length of 0 mm and a side length of 148 mm perpendicular to the same (area of 310.8 cm ² ) (meaning a film having a size conforming to the standard size A5 of Japanese Industrial Standards, hereinafter referred to as “A5”) Abbreviated as “per plate”) 25 μm
The above foreign substances do not exist and the number of foreign substances having a size of 5 μm or more and less than 25 μm is 10 or less.

The MOR (Maximum Oriented Ra) measured by the above-mentioned microwave transmission type molecular orientation meter.
tio) value needs to be in the range of 1.3 to 1.8, particularly preferably in the range of 1.35 to 1.75. It is preferable that all of the MOR values measured at three points in the width direction of the film satisfy the above range. The MOR value was measured at a central point in the width direction of the film and at one-fifth of an end connecting the central part and both ends of the film.
10 from one end of the straight line in the width direction of the film
%, 50% and 90%.

The MOR value is measured in the above three locations in the film width direction. In the film length direction (perpendicular to the width direction), for example, 1.0 times or more of the film width length. Measurement points can be selected at intervals of 5 times, preferably 2 to 3 times.

Here, the MOR value is a ratio (maximum value / minimum value) of the maximum value and the minimum value of the transmitted microwave intensity measured by the transmission type molecular orientation meter. The MOR value is smaller as the difference between the stretching ratio in the longitudinal direction and the transverse direction is smaller and the film is more balanced, while the difference between the stretching ratio in the longitudinal direction and the transverse direction is larger and the stronger the stretching strength in any one direction, the larger the MOR value. Become. This MOR value tends to change in the film width direction, and it is necessary that the difference (the difference between the maximum value and the minimum value) at the measurement points (three points) in the film width direction is 0.2 or less. And particularly preferably 0.15 or less.

The base film used for the release film of the present invention has a retardation value (R) defined by the following formula (1) of 1200 nm or more.

[0029]

R = △ n · d Equation (1) (where, in Equation (1), Δn is the visible light (wavelength λ) of the film.
= 589 nm), the difference (nx-ny) between the refractive index (nx) in the film width direction and the refractive index (ny) in the direction perpendicular to the film width, and d is the thickness (nm) of the film. The biaxially oriented polyester film is a birefringent body. When light enters, the incident light propagates as two linearly polarized lights whose vibration planes are orthogonal to each other. The difference between the two linearly polarized lights (ordinary ray and extraordinary ray) is called a phase difference (retardation: R), and this phase difference has an effect as a color and as an interference color in a polarizing plate inspection process.

Michel-Le in orthogonal Nicols
According to the interference color chart (polarized light microscope) of the vy renovation, it is dark field (black) in the low retardation area, and the interference color changes from yellow → red → purple → blue → green in proportion to this retardation, It returns to yellow again and the same cycle is repeated. However, according to the study of the present invention, the density of the interference color sharply decreases around the time when the retardation R exceeds 1200 nm. Therefore, when the retardation R is sufficiently large, the interference color is extremely small, and the visual inspection is performed. Turned out to be an obstacle. Therefore, the optimal range of the optical retardation value (R) is 1200 (nm) or more, and the film thickness usually used is 25 to 50 μm.
1300 in the case of biaxially oriented polyester film of
(Nm) or more was found to be most preferable for the release film.

In support of this requirement, the ratio (I / I ₀ ) of the amount of transmitted light (I) and the amount of incident light (I ₀ ) under crossed Nicols of a transparent plate having birefringence is generally expressed by the following equation (3). Is shown.

[0032]

(I / I ₀ ) = Sin ² (2θ) · Sin ² (π · △ n · d / λ) Equation (3) The amount of transmitted light and the amount of incident light in the crossed Nicols of a transparent plate having birefringence. The ratio becomes the extinction position as the existing angle of the birefringent body between Nicols (θ: corresponding to the orientation angle in the present invention) is smaller.

Conditions for the extinction position include the following (a) and (b). (A) When θ is small (b) Δn
When d / λ = R / λ is a natural number 1, 2, 3,... (R
Is an integral multiple of the light source wavelength: λ) As the orientation angle θ is closer to zero, the ratio of the above formula (2) becomes closer to zero and becomes the extinction position, and the foreign matter appears white,
The efficiency of visual inspection is most improved. At the same time, the retardation R has an average of 5 in the visible light wavelength range of 420 nm to 760 nm.
A multiple of about 90 nm is preferable, and R = 1200 (nm)
In the case of, the extinction position can be further increased under the horizontal orientation condition where the orientation angle θ is small, and when the retardation R is larger than that, the light interference density sharply decreases in the interference color chart in the orthogonal Nicols, so that R is 1200 nm. The above conditions are necessary conditions as foreign matter inspection conditions.

Although the upper limit of the retardation R depends on the film thickness, it is not necessary to set the upper limit particularly when the thickness is in the range of 25 μm to 50 μm.

The polyester film used for the base film in the present invention has no foreign matter of 25 μm or more per A5 plate, and one foreign matter of 5 μm to less than 25 μm.
There are no more than zero. 25 per base film A5
If foreign matter of more than μm exists, or more than 5 μm and 25μ
If the number of foreign substances less than m is 11 or more, there is no foreign substance at the time of foreign substance inspection of the polarizing plate, the retardation polarizing plate, or the laminate of the retardation film and the release film, and there is no problem in quality. Since the polarizing plate, the phase difference polarizing plate or the phase difference plate is determined as a defective product, the yield is remarkably reduced. still,
The number of foreign matters having a size of 5 μm or more and less than 25 μm per 5 base film A is preferably 3 or less, particularly preferably 1 or less. It is preferable that the number of the foreign matters is small, because the yield of the polarizing plate, the phase difference polarizing plate or the phase difference plate is improved.

It is to be noted that a polarizing plate, a retardation polarizing plate, or a retardation plate having foreign matter having a size of less than 5 μm or a foreign material having a size of 5 μm or more and less than 25 μm present in the A5 plate is 10 or less. Since there is no particular problem even if it is subjected to manufacture, foreign substances having a particle size of less than 5 μm may be present in the base film. It may be.

Here, the foreign matter in the present invention is a foreign matter which can be optically detected by a visual inspection by the cross Nicol method. For example, an inorganic or organic lubricant compounded at the time of manufacturing a polyester film may be agglomerated. And coarse particles, and foreign substances generated or mixed in the process of manufacturing the polyester film.

The size of the foreign matter in the present invention is measured as follows. That is, the foreign matter in the biaxially stretched polyester film optically detected in the visual inspection by the cross Nicol method is separately observed with transmitted light using an optical microscope, and the portion observed as an optically abnormal area is observed. The maximum diameter is the size of the foreign matter. For example, when a film is stretched, a void (void) is formed around a foreign substance or the like which is agglomerated by aggregating a lubricant. If the cavity is observed as an optically abnormal range, the size of the foreign substance is reduced. Included. The number of foreign substances was measured by measuring the sample film to a size (210 m in length) according to the standard base paper size A5 of Japanese Industrial Standards.
mx 148 mm wide: 310.8 cm ² area), and the number of foreign substances in the whole area of the film was measured.

The polyester film used as the base film preferably has the following characteristics in addition to the above characteristics.

(1) Transparency suitable for visual appearance inspection. Flatness to make the adhesive surface uniform. The light transmittance of the biaxially oriented polyester film is preferably 80% or more, particularly preferably 85% or more. When the light transmittance is within this range, the foreign matter can be easily identified when the release film of the present invention is laminated on the polarizing plate, the retardation polarizing plate or the retardation plate and the foreign matter inspection is performed by the cross Nicol method. Can be.

(2) Heat resistance, high strength elongation and high elasticity to withstand lamination of the adhesive film and the polarizing film performed under high tension heating. For example, it preferably has the following elongation at break, elastic modulus and heat shrinkage. Film breaking elongation: 100-250% in the length direction 50-150% in the width direction Film elastic modulus: 300-700 kg / m in the length direction
m ² width direction 400 to 800 kg / mm ² film heat shrinkage: length direction 1.0% or less (110 ° C.
0.5% or less in width direction (110 ° C × 30 minutes)

(3) Dimensional stability such that tunneling (sagging phenomenon), curling, and the like caused by generation of a deviation from the adhesive interface due to heat shrinkage of the release film do not occur.

(4) Thickness: 25 to 50 μm The polyester film used in the present invention is preferably a biaxially oriented film, and can be obtained, for example, by the following method. That is, the polyester is melted and cast on a cooling drum to form an unstretched film. Then, the unstretched film is heated at a temperature not lower than the secondary transition point (Tg) of the polyester at −10 ° C., for example, in the longitudinal and transverse directions. They can be obtained by biaxial stretching in a range of not less than 2.5 times and not more than 6 times, respectively. At this time, the stretching ratio in the vertical direction is 0.5 or more, more preferably 0.7 or more than the stretching ratio in the horizontal direction, or the stretching ratio in the horizontal direction is 0.5 or more than the stretching ratio in the vertical direction, and more preferably 0.5 mm or more. It is preferably larger by 7 or more.

The biaxial stretching may be a simultaneous biaxial stretching method or a sequential biaxial stretching method, but the latter is preferred. Then, it is preferable to add a boriding treatment means such as reducing bowing in the entire width of the film at the time of heat setting treatment after biaxial stretching. The film after biaxial stretching and heat setting has a heat shrinkage ratio of 4 in both the vertical and horizontal directions when held at 150 ° C. for 30 minutes (no load).
% Is preferable.

[Release Layer] In the present invention, a release layer containing an addition polymerization type silicone resin as a main component is provided on at least one surface of the polyester film. This silicone resin has an absorption peak height (H) at a wave number of 2800 to 3000 cm ⁻¹ due to —CH ₃ observed in an infrared absorption spectrum.
a) and the wave number 2100 belonging to the stretching vibration of -SiH
The ratio of the peak height (Hb) of the absorption peak at 2300 cm ^-1 satisfies the following expression (2).

[0046]

0 ≦ Hb / Ha ≦ 0.05 (2) If the above Hb / Ha exceeds 0.05, then -S in the coating film
The concentration of the component having the iH group is too high, and the component having the -SiH group in the release layer of the release film while the release film and the pressure-sensitive adhesive coated on the polarizing plate or the like are stored for a long time while being laminated. And the pressure-sensitive adhesive component act to cause a problem that separation and separation become difficult, and unreacted substances and the like present in the release layer of the release film are transferred to the surface of the pressure-sensitive adhesive, and the pressure-sensitive adhesive Significant drawbacks of reduced force occur.

In the present invention, the silicone resin constituting the release layer is, for example, a polydimethylsiloxane having a vinyl group represented by the following formula (A) and a hydrogensilane-based compound represented by the following formula (B): It can be obtained by addition polymerization using a system compound as a catalyst.

[0048]

Embedded image

In the above formula (A), m and n are numbers of 1 or more, where m is 1 to 100, n is 20 to 5000, and m + n
Is in the range of 30 to 5000, since the crosslinking reaction proceeds appropriately and a release layer excellent in durability can be obtained.
Note that in the above formula (A)

[0050]

Embedded image

It should be understood that does not mean block connection, but merely indicates that the sum of the respective units is m, n. Therefore,
Each unit in the above formula (A) may be randomly bonded, or may be block-bonded.

[0052]

Embedded image

In the above formula (B), a and b are 1 or more, and a is 3 to 200, b is 1 to 120, and 5 ≦ a + b
A range of ≦ 200 is preferable because the crosslinking reaction proceeds appropriately and a release layer having excellent durability can be obtained. Note that, in the above equation (B),

[0054]

Embedded image

It should be understood that does not mean block connection, but merely indicates that the sum of the respective units is a and b. Therefore,
Each unit in the formula (B) may be randomly bonded, or may be block-bonded.

The vinyl group used in the above addition polymerization has a vinyl group.
Polydimethylsiloxane and hydrogen silane
The proportion of the compound is based on polydimethylsiloxane having vinyl groups.
Hydrogen is added to 1.0 mole of vinyl group in xane.
When the amount of the SiH group in the silane compound is 1.0 to 2.0 mol,
It is necessary that the ratio be Addition polymerization referred to here
Means ~ Si-CH = CH_TwoA molecular terminal represented by or
Functional group in molecular side chain and molecular terminal represented by H-Si
Or the functional group in the side chain of the molecule is ~ Si-CH _TwoCH_Two
-Si is a polymerization reaction. However, the above reaction
In the formula, “〜” indicates that the molecules are further connected.

In the present invention, as the silicone resin constituting the release layer, a silicone resin having a ratio of the absorption peak height (Ha) to the absorption peak height (Hb) recognized in the infrared absorption spectrum satisfying the above formula (I) is used. However, such a silicone resin can be obtained, for example, by the following methods (1) to (3).

(1) When the silicone resin constituting the release layer is obtained, the ratio of the vinyl group-containing polydimethylsiloxane used for addition polymerization to the ratio of the hydrogen silane compound to the vinyl group-containing polydimethylsiloxane is as follows. It is used in such a ratio that the amount of the SiH group in the hydrogen silane compound is less than 1.0 mol with respect to 1.0 mol of the vinyl group.

(2) A large amount of a Pt catalyst is used in order to reduce the ~ SiH residue in the silicone resin constituting the release layer by the following reaction.

[0060]

Embedded image _{a) ~SiH + H 2 O →} ~SiOH + H 2 b) ~SiH +1/2 O 2 → ~SiOH c) ~SiH + HOSi~ → ~SiOSi~ + H 2 d) ~SiOH + HOSi~ → ~SiOSi~ + H 2 O

(3) Post-curing is performed at 40 to 50 ° C. to promote the reaction of the SiH residue in the silicone resin.

In the method (1), when the number of SiH groups is reduced, the crosslink density of the silicone resin is reduced, so that the durability of the coating film may be reduced. Therefore (2)
And / or the method (3) is preferably employed.

In the method (2), the Pt-based compound is used as a catalyst for addition polymerization, and the amount of the Pt-based compound is adjusted so that the concentration of the Pt-based compound in the release layer is 1 to 50 as a Pt metal element.
The amount is preferably 0 ppm. If the amount of the Pt metal element is less than 1 ppm, the addition polymerization may not proceed at a desired ratio, so that the release film and the pressure-sensitive adhesive coated with a polarizing plate or the like may be separated during a long-term storage while being laminated. Unreacted substances and the like present in the release layer of the mold film may be transferred to the surface of the pressure-sensitive adhesive layer, resulting in a decrease in the adhesive strength. On the other hand, when the amount of the Pt metal element exceeds 500 ppm, gelation progresses during storage of the coating liquid used for coating the release layer, so that the so-called pot life is shortened, and the product may not be suitable for production. Examples of the Pt-based compound include a platinum complex soluble in silicone oil, an alcohol-modified platinum complex (an alcohol solution of chloroplatinic acid), and a methylvinylpolysiloxane platinum complex.

In the method (3), a coating liquid containing polydimethylsiloxane having a vinyl group and a hydrogen silane compound is applied to at least one surface of the polyester film, and heated to cause an addition polymerization reaction. After coating the film, the heating temperature T (° C.) and the heating time θ (H
r) is to perform post-curing under the following conditions.

[0065]

## EQU8 ## T × θ ≧ 1000 [° C. · Hr] 23 ≦ T ≦ 50 [° C.]

[Other Compounding Agents] Various known additives can be added to the release layer in the present invention as long as the object of the present invention is not hindered. Examples of the additive include an ultraviolet absorber, a pigment, an antifoaming agent, a pot life extender, a crosslinking agent, and the like.

[Method of Coating Release Layer] In the present invention,
A release layer is provided on at least one surface of the polyester film. The release layer may be, for example, a polydimethylsiloxane having a vinyl group represented by the formula (A) or a compound represented by the formula (B).
Can be provided by applying a coating liquid containing a hydrogen silane-based compound and a Pt-based compound represented by the formula (1) to a film, followed by drying and curing reaction by heating. The conditions of this heating are, for example, 80-160 ° C. and 10-120.
It is preferable to set the drying time and the curing time at 100 to 150 ° C. for 15 to 60 seconds, because the drying and curing reaction become sufficient. In addition, as a coating method of the coating liquid, any known coating method can be applied, and examples thereof include a roll coater method and a blade coater method, but are not limited to these methods. Further, the coating liquid may be a coating liquid using an organic solvent, may be an aqueous coating liquid, it is preferably a solution in which polydimethylsiloxane or hydrogen silane compound is dissolved, for example, toluene and the like The coating liquid using an organic solvent is preferable.

The thickness of the cured silicone resin coating is not particularly limited, but is preferably in the range of 0.05 to 0.5 μm. If the thickness is too small, the release performance is reduced, and satisfactory performance cannot be obtained. On the other hand, if the thickness is too large, it takes a long time for curing, which causes inconvenience in production.

[Adhesive Layer] In the present invention, an adhesive layer is provided on at least one surface of the polyester film in order to enhance the adhesion between the polyester film and the release layer, and a release layer is further laminated on the adhesive layer. be able to. For this adhesive layer, for example, a silane coupling agent can be preferably used. As the silane coupling agent include those represented by the general formula Y-Si-X _3. Here, Y represents a functional group represented by, for example, an amino group, an epoxy group, a vinyl group, a methacryl group, a mercapto group, and X represents a hydrolyzable functional group represented by an alkoxy group. The preferable thickness of the adhesive layer is 0.01 to 5 μm.
m, and particularly about 0.02 to 2 μm. When the thickness of the adhesive layer is in the above range, the adhesion between the polyester film and the release layer becomes good, and the polyester film provided with the adhesive layer is hard to block, so that there is hardly any trouble in handling.

The release film of the present invention is used by being laminated on the surface of a polarizing plate, a retardation polarizing plate or an adhesive layer provided on one side of a retardation plate. Are laminated so that the surfaces of the silicone resin coating films are in contact with each other.

The above laminate obtained by laminating the release film is
The direction of the principal axis of the crystal orientation of the biaxially oriented polyester film in the release film measured by the microwave transmission type molecular orientation meter is substantially the same as the direction of the orientation axis of the polarizing plate, retardation polarizing plate or retardation plate. It is necessary that they are aligned so as to be equal to each other or they are positioned so as to be 90 °. Here, “substantially the same” means that the two directions may be completely coincident or slightly deviated to such an extent that the visual inspection is not substantially hindered. Usually, a deviation of 5 ° or less, preferably 3 ° or less, is acceptable.

In general, the crystal orientation principal axis of a biaxially oriented polyester film measured by a microwave transmission type molecular orientation meter (hereinafter, this may be simply referred to as “orientation principal axis”).
Of the film substantially coincides with the longitudinal direction (longitudinal direction) or the lateral direction (width direction) of the film, for example, the longitudinal direction of the film and the longitudinal direction (length) of the polarizing plate, the retardation polarizing plate or the retardation plate. (The orientation direction; the orientation axis direction), the lamination conditions can be satisfied.

In the above laminate, the alignment principal axis of the release film coincides with or deviates by 90 degrees from the alignment axis of the polarizing plate, the retardation polarizing plate or the retardation plate. No color is generated, and foreign matter and defects can be easily detected. In addition, the orientation main axis of the film and the polarizing plate,
Inspection in the bright field is performed when the orientation axis of the retardation polarizing plate or the retardation plate is coincident, and inspection is performed only in the reflected light in the dark field when the orientation axis is shifted by 90 degrees. Inspection is easy. For example, length 900mm, width 6
Inspection is easy even with a size of 00 mm, and almost no foreign matter or defect is overlooked.

As the polarizing plate, the retardation polarizing plate, the retardation plate, and the pressure-sensitive adhesive layer laminated thereon, those conventionally known can be used. Among these, the polarizing plate, the phase difference polarizing plate, and the phase difference plate are preferably a large-screen TFT (active matrix) type or STN (super twisted nematic) type.

FIG. 1 is a schematic diagram showing the structure of a laminate using the release film of the present invention and the state of a visual inspection.
In FIG. 1, reference numeral 1 denotes a laminated structure, 2 denotes a protective film, for example, a polyethylene film having a thickness of 50 to 70 μm, and 3 denotes a polarizing plate (or a retardation polarizing plate or a retardation plate).
20-200 μm thickness, 4 is an adhesive layer, usually 20-50
μm thickness, 5 is a silicone release layer, 6 is a biaxially oriented polyester film, 7 is a polarizing plate for cross Nicol inspection, 8
Denotes a milky light diffusion plate, and 9 denotes a light source, for example, two fluorescent lamps 20W. The laminate 1 is composed of a structure from a protective film to a biaxially oriented polyester film 6, and the release film is composed of a silicone release layer 5 and a biaxially oriented polyester film 6.

[0076]

EXAMPLES The present invention will be further described below with reference to examples. In addition, each characteristic value of the film was measured by the following method.

[Characteristics of Biaxially Stretched Film] 1. MOR value, inclination of main axis of crystal orientation (orientation angle) Using a microwave molecular orientation meter manufactured by Kanzaki Paper Co., Ltd., biaxial orientation from the pattern of transmitted microwave intensity. The MOR value of the polyester film sample and the inclination (orientation angle) of the crystal orientation main axis were determined.

2. Refractive index (nx: longitudinal direction, n) of the retardation film in visible light (wavelength λ = 589 nm)
y: lateral direction) and the film thickness (d: nm) were measured, and the retardation value (R) was determined by the following equation (1).

[0079]

R = △ n · d Equation (1) (where, in Equation (1), Δn is the difference between the refractive index (nx) in the vertical direction and the refractive index (ny) in the horizontal direction of the film. (Nx
-Ny), and d is the thickness (nm) of the film. )

3. Light transmittance Using a HR-100 haze meter manufactured by Murakami Color Research Laboratory, a light beam having a wavelength of nm was incident on the film, and the ratio of the total transmitted light amount to the incident light amount was defined as the light transmittance.

4. Measurement of the number of foreign substances The biaxially oriented polyester film sample was measured in accordance with the standard base paper size A5 of Japanese Industrial Standards (length 209 to 21).
0 mm × horizontal 148～149Mm: area of about 310 cm ²⁾
The whole area of the film was inspected for foreign substances by visual inspection using the cross Nicol method. Next, the detected foreign matter in the sample film was observed with transmitted light using an optical microscope, and the maximum diameter of a portion observed as an optically abnormal range was defined as the size of the foreign matter. When a cavity (void) existing around the foreign matter is observed as an optically abnormal range, it is included in the size of the foreign matter. Further, the size of the foreign material was divided into those having a size of 25 μm or more and those having a size of 5 μm or more and less than 25 μm, and the number of foreign materials per A5 plate was measured.

[Characteristics of Release Film] The shrinkage in the longitudinal and transverse directions of the release film when held under the conditions of a heat shrinkage of 150 ° C. for 30 minutes was measured.
The heat shrinkage is from -0.5% to + 0.5%, especially -0.3%.
% To + 0.3%. When the heat shrinkage is in this range, it is possible to prevent the flatness of the release film from being lost due to shrinkage caused by heating (heating for removing the solvent) when the pressure-sensitive adhesive layer is applied to the release layer surface.

6. Infrared absorption spectrum Conversion of silicone resin used for release layer to methyl ethyl ketone
Dissolve so that the solid content concentration becomes 3% by weight solution.
On the surface of polyethylene terephthalate film
And apply at 150 ° C with a hot air dryer.
After drying for 20 seconds, FTIR (JASCO, He
rschel FT / IR700) by Zi-S
Measure the infrared absorption spectrum by the ATR method using e
You. From the obtained composite infrared absorption spectrum, polyethylene
By subtracting the absorption peak derived from terephthalate,
An infrared absorption spectrum derived from the silicone resin is obtained. This
From the infrared absorption spectrum derived from the silicone resin of
Wave number 2800-3000cm ^-1Peak height (H
a) and a wave number of 2100 to 2300 cm^-1Absorption peak height
(Hb). Hb / Ha is calculated from the obtained value.
Was.

7. Peel strength A polyester adhesive tape (Nitto 31B) is adhered to the release layer surface of the polyester film, pressed with a 5 kg pressure roller, left at 40 ° C. for 20 hours, and then the peel force (R _f0 ) between the release layer and the adhesive tape is _measured . It was measured by a tensile tester.

The preferable range of the peel strength is 2 to 30 g.
/ In, further 2 to 10 g / in, especially 2 to 10 g
/ In. When the peel strength is less than 2 g / in, the laminated body laminated with an adhesive coated on one side of a polarizing plate or the like is punched into various sizes and cut, or the end face of the laminated body is subjected to foreign substance inspection. In this case, the release film is undesirably rolled up from the surface of the pressure-sensitive adhesive layer. On the other hand, if the peel strength exceeds 30 g / in, peeling may be difficult when the release film is peeled and separated from the laminate, which is not preferable.

8. Residual Adhesion Rate The peeling force after attaching a polyester pressure-sensitive adhesive tape (Nitto 31B) to a cold-rolled stainless steel plate (SUS304) specified in JIS G4305 is measured and defined as a basic adhesive force (f ₀ ). Further, the polyester adhesive tape was pressed against the surface of the sample film on which the release layer was applied with a 5 kg pressure roller, left for 30 seconds, and then the adhesive tape was peeled off. Then, the peeled adhesive tape is stuck on the stainless steel plate, and the peeling force of the stuck portion is measured.
Residual adhesive strength (f). Obtained basic adhesive strength (f ₀ )
And the residual adhesive force (f), the residual adhesive ratio is determined using the following equation.

[0087]

Equation 10] Residual adhesion ratio (%) = (f / f 0) × 100 Note that, preferably as residual adhesion ratio is large, a preferred range is 85% or more, preferably 90% or more. 8 residual adhesion
When the content is less than 5%, for example, when the release film is rolled and stored, components constituting the release layer are transferred to the surface of the adjacent film (so-called backside transfer), and the characteristics of the release layer are reduced. It is not preferable because the properties such as the adhesiveness of the adjacent film surface may be deteriorated or the properties may be deteriorated.

9. Time-dependent heavy release rate A polyester adhesive tape (Nitto 31B) is adhered to the release layer surface of the polyester film, pressed with a 5 kg pressure roller, left at a temperature of 23 ° C. for 30 days, and then peeled from the release layer and the adhesive tape. The force (R _f1 ) was measured by a tensile tester, and the rate of heavy release over time was calculated from the release force (R _f0 ) between the release layer and the adhesive tape measured by the above-described method of measuring the peel strength, using the following formula. Ask.

[0089]

[Equation 11] The rate of heavy release over time (%) = R _f1 / R _f0 × 100 The preferred range of the rate of heavy release over time is 90% to 110.
%. If the time-dependent heavy peeling rate exceeds 110%, for example, a laminate in which a pressure-sensitive adhesive layer coated on one surface such as a polarizing plate is bonded to the surface of a release film is stored at 40 ° C. for a long time (for example, for 6 months). In this case, when the release film is peeled and separated from the laminate and used, the peeling may be difficult, which is not preferable.

[Evaluation of laminated body] Visual Inspection Status (Effect of Optical Interference under Crossed Nicols) A visual inspection was performed using the configuration shown in FIG. Good: Visual inspection No light interference occurred Slightly poor: Visual inspection Light interference occurred but inspection is possible Poor: Visual inspection Light interference occurred and inspection impossible

11. Visual inspection status (defective product detection rate) The laminated product (protective film, polarizing plate, adhesive layer, release layer and biaxially oriented polyester film) was visually inspected with the configuration shown in FIG. Extracted. Next, a visual inspection of the polarizing plate (protective film, polarizing plate and adhesive layer) obtained by peeling off the release film (release layer and biaxially oriented polyester film) from the laminate extracted as a defective product was performed. The defective product of the polarizing plate was extracted, and the defective product detection rate when measured with the laminate was calculated and evaluated according to the following criteria. Good: Defective product detection rate is 90% or more Slightly poor: Defective product ratio is 50% or more and less than 90% Defective: Defective product ratio is less than 50% or cannot be inspected

Example 1 100 parts by weight of polyethylene terephthalate was used as a lubricant by an air classifier to obtain 25 parts by weight.
Alumina particles from which aggregated particles of μm or more are removed 0.00
The polyester composition containing 5 parts by weight is supplied to an extruder (a sintered metal filter is provided between the tip of the extruder and a die), and the molten polyethylene terephthalate is extruded into a film and rotated at 20 ° C. It was brought into contact with a cooling drum and rapidly cooled to obtain an unstretched film. Subsequently, the unstretched film was successively biaxially stretched at a stretching ratio shown in Table 1, and further heat-fixed under the conditions shown in Table 1 to a thickness of 38 μm and a total width of 219.
A 0 mm biaxially oriented polyethylene terephthalate film was obtained. Table 1 shows the measurement results of the MOR value, the difference between the maximum value and the minimum value of the MOR value, the retardation value (R), the light transmittance and the number of foreign substances of the biaxially oriented polyethylene terephthalate film.

Next, in the above formula (A), m is 10,
A mixed solution of a polydimethylsiloxane in which n is 2000 and a hydrogensilane-based compound in the formula (B) wherein a is 100 and b is 10 (1.0 mol of ~ SiH groups in the hydrogensilane-based compound) On the other hand, a Pt catalyst (methanol solution of chloroplatinic acid) was obtained at a ratio of 70 pp as a Pt metal to a silicone polymer from which a Pt catalyst (methanol solution of chloroplatinic acid) was obtained.
m, and a toluene solution having a total solid content of 3% was prepared.

This solution was applied to a biaxially stretched polyethylene terephthalate film (thickness: 38 μm) at 6 g / m ² (we
t) coating temperature, heating temperature 140 ° C, heating time 1
After a minute, the film was dried and subjected to an addition polymerization reaction to prepare a release film. Table 1 shows the characteristics of the release film.

Further, a laminate having the structure shown in FIG. 1 was prepared using this release film, and the polarizing plate was visually inspected.
Table 1 shows the evaluation results of the laminate.

In Table 1, the symbols B, C, and F indicate that the entire width (2190 mm) of the film is slit into three equal parts (730 mm). B: The film portion on the left side when viewed from the winding position of the film. Film portion F at the center when viewed from the film winding position: The right film portion when viewed from the film forming position.

[Example 2] The amount of Pt catalyst to be added was 10 pp as Pt metal with respect to the obtained silicone polymer.
m, and after a drying and addition polymerization reaction were carried out at a heating temperature of 140 ° C. and a heating time of 1 minute, a release film was prepared in the same manner as in Example 1 except that post-curing was further carried out at 40 ° C. for 72 hours. Table 1 shows the characteristics of the release film and the evaluation results of the laminate using the release film.

[Comparative Example 1] The amount of the Pt catalyst to be added was 10 pp as Pt metal with respect to the obtained silicone polymer.
A release film was prepared in the same manner as in Example 1 except that m was used. Table 1 shows the characteristics of the release film and the evaluation results of the laminate using the release film.

[Comparative Example 2] The amount of Pt catalyst to be added was 10 pp as Pt metal with respect to the obtained silicone polymer.
m, and a drying and addition polymerization reaction was performed at a heating temperature of 140 ° C. and a heating time of 1 minute, and then a release film was prepared in the same manner as in Example 1 except that post-curing was further performed at 23 ° C. for 24 hours. Table 1 shows the characteristics of the release film and the evaluation results of the laminate using the release film.

[Examples 3 and 4 and Comparative Examples 3 to 6] A thickness of 38 μm and a total width of 2 were obtained in the same manner as in Example 1 except that the stretching ratio and the heat setting temperature were changed to the conditions shown in Table 1 or Table 2.
A 190 mm biaxially oriented polyethylene terephthalate film was obtained. The properties of these biaxially oriented polyethylene terephthalate films are shown in Table 1 or Table 2.

Next, a silicone resin coating was applied to one surface of the biaxially oriented polyethylene terephthalate film in the same manner as in Example 1 to obtain a release film having sufficient release characteristics. Using the film, a laminate was prepared in the same manner as in Example 1, and each characteristic was evaluated. The results are shown in Table 1 or Table 2.

The film used in Comparative Example 1 and the film used in Example 3 are obtained by dividing the formed film into three equal parts in the width direction. That is, the film (B) of Comparative Example 1 is the film portion on the left side when viewed from the winding position of the film forming film, and the films (C and F) of Example 3 are the film portion at the center when viewed from the same winding position. And the right film part. The difference between the MOR value and the difference between the maximum value and the minimum value of the MOR value in spite of the film cut in the length direction from the same film formed as described above is due to the bowing phenomenon at the time of film formation. It is presumed that the orientation main axis changes depending on the position.

Comparative Example 7 A biaxially stretched polyester film was prepared in the same manner as in Example 1 except that a sintered metal filter was not mounted, and a release film and a laminate were further formed in the same manner as in Example 1. We made and evaluated each characteristic. Table 2 shows the results.

Example 5 Polyethylene-2,6-naphthalenedicarboxylate was used in place of polyethylene terephthalate, and the temperature of the rotary cooling drum was set to 50 ° C.
A biaxially oriented polyethylene-2,6-naphthalenedicarboxylate film having a thickness of 38 μm and a total width of 2190 mm was obtained in the same manner as in Example 1 except that the film was stretched and heat-set under the conditions shown in Table 2. Table 2 shows the properties of the biaxially oriented polyethylene-2,6-natalenedicarboxylate film.

Next, the biaxially oriented polyethylene-2,
A silicone resin coating solution was applied to one surface of the 6-natalenedicarboxylate film in the same manner as in Example 1, dried and cured to obtain a release film having a coating film thickness of 0.24 μm. Table 2 shows the characteristics of the release film. Further, a laminate was prepared using this release film in the same manner as in Example 1, and each characteristic was evaluated. The results are shown in Table 2.

[0106]

[Table 1]

[0107]

[Table 2]

As is evident from the results shown in Tables 1 and 2, the release film of the present invention is excellent in peel strength, residual adhesion rate and time-dependent heavy peeling rate, and is extremely useful for visual inspection of a polarizing plate. Was something.

[0109]

When the release film obtained by the present invention is laminated on a polarizing plate, a retardation polarizing plate or a retardation plate and used for foreign substance inspection by the crossed Nicols method, the light interference color in the crossed Nicols is substantially changed. This makes it possible to easily perform a visual inspection of foreign substances, to improve the accuracy of foreign substance inspection even for a large-screen LCD, and to prevent the occurrence of defective products.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a configuration of a polarizing plate foreign matter visual inspection.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 polarizing plate laminate, retardation polarizer laminate or retardation plate laminate 2 protective film 3 polarizing plate (stretching axis: lateral direction), retardation polarizer or retardation plate 4 adhesive layer 5 silicone release layer 6 2 Axis-oriented polyester film 7 Polarizing plate for cross Nicol inspection 8 Opalescent light diffusing plate 9 Light source Arrows (←) indicate the longitudinal direction (longitudinal direction) of the film.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08J 7/04 CFD C08J 7/04 CFDZ // B29K 67:00 B29K 67:00 B29L 7:00 B29L 7: 00 C08L 67:00 C08L 67:00 F term (reference) 2H049 BA02 BA06 BB54 BC14 BC22 4D075 BB26Z CA07 CB06 DA04 DB48 DC24 EA07 EB42 EB43 EB51 EB56 4F006 AA35 AB39 BA11 CA00 4F207 AA24 AG01 AK02 KA01 KA01 KA01 KA01 KA01 AE02 AH33 QC06 QG01 QG18 QW07 QW50

Claims (4)

[Claims] After applying a coating liquid containing an addition polymerization type silicone resin to at least one surface of a polyester film,
A method for producing a release film in which a release layer containing a silicone resin as a main component is formed by heating and curing, wherein the polyester film has a retardation value (R) defined by the following formula (1) of 1200 ( nm) or more, the MOR value measured by a microwave transmission type molecular orientation meter is in the range of 1.3 to 1.8, and the difference between the minimum value and the maximum value of the MOR value is 0.2 or less, And one side length 210m
m and a width of 148 mm in the side perpendicular to it (area 3
10.8 cm ² ) of a film having no foreign matter of 25 μm or more, 10 or less foreign matters of 5 μm to less than 25 μm in the film, and a polydimethylsiloxane having a vinyl group before curing of the silicone resin; The ratio of the gensilane-based compound is such that the amount of the SiH groups in the hydrogensilane-based compound is 1.0 to 2.0 mol per 1.0 mol of the vinyl groups in the polydimethylsiloxane having a vinyl group. , wavenumber 2800～ by -CH ₃ observed in the infrared absorption spectrum of the silicone resin after curing
The absorption peak height (Ha) of 3000 cm ^-1 and -SiH
The method of manufacturing a polarizing plate, a retardation polarizing plate or a release film used for inspection of a retardation plate, wherein the ratio of the absorption peak height (Hb) at a wave number of 2100 to 2300 cm ^-1 satisfies the following formula (2). R = △ n · d Equation (1) (where, in Equation (1), Δn is the visible light (wavelength λ) of the film.
= 589 nm) and the difference (nx-ny) between the refractive index (nx) in the film width direction and the refractive index (ny) in the direction perpendicular to the film width, and d is the thickness (nm) of the film. 0 ≦ Hb / Ha ≦ 0.05 Equation (2) 2. The shrinkage in the vertical and horizontal directions when held at 150 ° C. for 30 minutes is -0.5% to + 0.5%.
The method for producing a release film according to claim 1, wherein 3. A biaxially stretched unstretched film obtained by extruding a polyester composition obtained by blending a polyester composition obtained by removing a lubricant in which a coagulated particle of 25 μm or more is removed from a polyester into an extruder and quenching it. The method for producing a release film according to claim 1, which is an oriented film. 4. The polyester film is a biaxially oriented film obtained by biaxially stretching an unstretched film obtained by extruding a polyester composition into a film form from an extruder equipped with a sintered metal filter and rapidly cooling the extruded film. A method for producing a release film according to claim 1.